The Chandra Levy murder mystery has transformed, again, into a broader debate over public access to court proceedings.

In legal filings Wednesday, news media organizations that include McClatchy, The Washington Post, the Associated Press and Gannett formally challenged a judge’s orders keeping potentially crucial new developments secret. The companies want access to future hearings and transcripts of past hearings that were closed, concerning a prosecution witness whose credibility now may be in question.

“In light of the total secrecy, news organizations . . . that have attempted to report on these developments have been left to speculate about what is happening,” attorney Patrick J. Carome wrote in a brief for the media companies.

Carome and his fellow attorney with the WilmerHale law firm, Steven P. Lehotsky, contend in their 15-page brief that the cloak of secrecy now draped over the new Levy trial developments frustrate the First Amendment rights of news organizations that “have devoted substantial journalistic resources to covering the criminal proceedings” in the long-running Levy drama.

Several of the media organizations involved in the new legal action, including the Reporters Committee for Freedom of the Press, previously devoted legal resources to opening other Levy case proceedings. Last January, responding to a media appeal, the District of Columbia Court of Appeals overturned the judge’s effort to keep juror questionnaires secret.

“The value of public trials is undisputed,” the D.C. Court of Appeals declared in the earlier decision. “The presence of the public and the press at criminal trials historically has been thought to enhance the integrity and quality of what takes place.”

A graduate student and former Bureau of Prisons intern, the 24-year-old Levy was preparing to return to her family’s home in Modesto, Calif., from Washington when she disappeared May 1, 2001. Rumors and then revelations that she’d been involved in a sexual relationship with then-Rep. Gary Condit, D-Calif., transformed her case into a national media sensation.

In November 2010, after the cold case was resurrected, a Washington jury convicted Ingmar Guandique of Levy’s murder. He’s serving a 60-year prison sentence.

Sometime late last year, Justice Department prosecutors brought information that could undermine the credibility of one of their witnesses to the attention of D.C. Superior Court Judge Gerald I. Fisher. The witness’s identity and the nature of the new information hasn’t been made public, and hearings Dec. 18 and Jan. 4 were conducted out of earshot of the sole reporter present.

“The possible disclosure of that information may create safety issues . . . that I have concluded are somewhat substantial here,” Fisher said at the Dec. 18 hearing.

The most important witness for the prosecution was a former Fresno, Calif., gang member named Armando Morales, who testified that Guandique had confessed to him while they were in the same prison.

“Given the circumstantial nature of much of the government’s case, the credibility of one of its witnesses is obviously of great importance,” the media organization’s brief notes.

Guandique’s defense attorneys have filed their own appeal challenging the trial judge’s secrecy orders. A spokesman for the U.S. Attorney’s Office declined to comment Wednesday.